An image sensor is generally subject to motion and vibrations which might distort a detected image of a scene. The motion can be linear, where the image sensor undergoes a linear displacement or scaling, and the motion can be angular, where the image sensor rotates about one or more axes. In case of an image sensor mounted on a marine vessel, the image can be distorted as a result of ocean waves. Likewise, image distortion can occur in images detected by an image sensor mounted to a ground vehicle, an airborne platform, such as an aircraft, a helicopter or a satellite.
Methods for compensating for the vibrations and noise in order to obtain a stabilized image are known in the art. For example, a gyroscope connected to the image sensor detects the inertial rotations of the image sensor, and a servo system (including a servo motor and a controller) rotates the gimbals on which the image sensor is mounted, in the opposite direction and by the same amount, according to the output of the gyroscope. The image can be further refined by employing additional gyroscopes and by providing each gyroscope additional degrees of freedom.
Prior art imaging systems are typically large in size and thereby in relative weight. Furthermore, prior art imaging systems require extensive image processing on the whole image frame acquired, particularly for high resolution imaging systems.
There is a need for and it would be advantageous to have image sensors, mounted on an airborne vehicle, such as unmanned aerial vehicle (UAV), having high resolution and capability to select in real the region-of-interest (ROI), low cost, low weight and low power consumption.